The objectives of this study are to determine whether animal pretreatment with compounds which modify enzyme levels will alter acute and/or chronic inhalation toxicity of selected solvents; to determine whether pretreatment of animals with solvents by inhalation alters subsequent degradation in lung and liver; to investigate metabolic pathways in the degradation of paraxylene and the effects of pretreatment by known enzyme inducers on these pathways; to identify urinary metabolites for use as biological indicators of paraxylene exposure; to study the effects of phenol on in vitro metabolism of benzene.